1. Field of the Invention
This invention relates to polymeric compositions that are highly functional polymers with a relatively high molecular weight and are substantially free of gelling. Moreover, when used in aqueous solution they provide a relatively low solution viscosity. The invention also relates to the preparation of such polymeric compositions. The polymeric compositions of this invention are particularly useful as polymeric support resins or compatabilizing additives, or for use in overprint varnishes, inks, pigment dispersions, powder coatings, adhesives and the like. The invention also relates to a deglossed acrylic epoxy hybrid powder coating and method of preparing the same, a powder coating composition comprising the polymeric compositions of this invention, as well as 100% solids resin inks.
2. Related Background Art
Polymeric compositions that are block copolymers having an A(BA)n structure are well known. For example, U.S. Pat. No. 5,362,819 describes an ABA curable block copolymer with an A block that is an unsaturated polyester, preferably having a mono-, or less desirably a di-, hydroxyl, carboxylic or amine end group, and a B block that is a flexible polymer having a glass transition temperature (Tg) of 0° C. or less. The flexible polymers are said to include those prepared from conjugated diene monomers, as well as polyethers or saturated polyester, which are linked to the A block by an ester, amide, urea or urethane group.
U.S. Pat. No. 4,347,339 describes a water soluble cationic block copolymer having a first polymer block having amino functional groups, a majority of which are quaternary amino groups, and a second polymer block having amino functional groups, a majority of which are not quaternary amino groups. The polymer blocks may be linked with bridges of other polymers, but are preferably linked by including a functional group such as a chloride or epoxide in the first polymer block that reacts with the amino functional groups of the second polymer block.
U.S. Pat. No. 4,851,474 describes a block copolymer comprising at least one polyester block and an elastomeric polymer block such as a polymer of one or more conjugated dienes. The elastomeric block is functionalized to incorporate only terminal functional groups, i.e., no more than 2 functional groups per polymeric block.
U.S. Pat. No. 5,008,334 describes resins containing an ABA block copolymer having an A block which is a reaction product of a diol and one or more diepoxides and a B block of an epoxy-capped, carboxyl-terminated polybutadiene or polybutadiene/acrylonitrile copolymer. Amine resins which are prepared from a resin that is a mixture of (i) the reaction product of a diol and at least one diepoxide and (ii) the ABA block copolymer are used in electrocoating formulations.
U.S. Pat. No. 5,314,954 describes aromatic polyester-polystyrene block copolymers produced by the polycondensation of styrene polymers having terminal functional groups, e.g. hydroxy, amino or carboxyl groups, with an excess of aromatic dicarboxylic acid dihalides and then subjecting the resulting condensation product to interfacial polymerization with aromatic dihydroxy compounds. These aromatic polyester-polystyrene block copolymers are said to have a minimum of uncopolymerized styrene and to be useful for the preparation of optical instruments.
Polyester block copolymers that provide an elastic yam having a high elastic recovery and a high heat resistance are disclosed by U.S. Pat. No. 5,384,184. The polyester block copolymer comprises (A) 30 to 90% by weight of polyester segments comprising a benzenedicarboxylic acid as the main acid component and a diol having 5 to 12 carbon atoms between the hydroxyl groups as the main glycol component and (B) 70 to 10% by weight of polyester segments comprising an aromatic dicarboxylic acid as the main acid component and ethylene glycol, trimethylene glycol, tetramethylene glycol or 1,4-cyclohexane dimethanol as the main glycol component.
U.S. Pat. No. 5,496,876 describes a polyetheramide block copolymer constituted by the copolycondensation of polyamide polymers having reactive end groups with polyether sequences having reactive end groups. These polyetheramide block copolymers are blended with a styrene/diene copolymer to form thermoplastic polymeric compositions.
U.S. Pat. No. 4,180,528 describes an ABA type block copolymer having an A block that is an addition polymer and a B block that is a linear saturated polyester. The A block and B block are joined by addition polymerization.
European Patent Application Publication No. 0687690/A describes a high temperature polymerization process to produce terminally unsaturated oligomers having relatively low molecular weights. It is further disclosed that the terminally unsaturated oligomers having a carboxylic acid group can be reacted with polyfunctional alcohols having two or more alcohol functionalities to form polyesters. There is, however, no disclosure of terminally unsaturated oligomers having relatively high functionality.
One particular use of polymeric compositions is as 100% solids resin. 100% solids resin compositions have many possible applications. For example, powder coating processes are well known and are typically fusion-coating processes in that powder particles are fused or melted at some point in the process. Powder coating processes are often advantageous because of their essentially nonvolatile nature. The powder (“coating powder”) used in the powder coating process is coated onto a substrate surface, melted or fused to form a continuous coating, and cooled to harden the resultant coating. The heat can melt the powder to consolidate the powder to a coating film, or can cause the powder to react together, as in a polymerization or curing process, to consolidate the powder to a coating film.
One type of coating powder uses acid functional acrylic resins in its formulation. Such acrylic formulations are commonly formulated with epoxy to make what is known as acrylic epoxy hybrid powder coatings. An example of such an acrylic resin being used for this purpose is SCX-819, available from Johnson Polymer, Inc., Sturtevant, Wis., which has found wide use in the appliance market. However, the use of acrylics could be extended into other powder coating applications with the development of 100% solids resin polymers that have improved flexibility, and improved polyester compatibility, and by finding ways to degloss acrylic hybrids without sacrificing mechanical properties.
Another possible use of 100% solids resin compositions is as plastic additives. Plastics additives are commonly used in the polymer industry. Additives are used as compatibilizers, thickeners, plasticizers, coextrusion additives to improve extrusion rheology and extruded product properties. Solid resins have also been used as hot-melt adhesives.
100% solids resin inks are mixtures of pigment components dispersed or dissolved in 100% solids resin carrier components. 100% solids resin inks are commonly used in applications such as letterpress, dry offset, lithography and as toners for xerography.
Polymeric compositions, e.g., block copolymers, that are highly functional, preferably having high acid functionality, as well as a high molecular weight, but which do not readily gel would be highly desirable, particularly for the uses described above.